Synthesis of electrically conductive and superparamagnetic monodispersed iron oxide-conjugated polymer composite nanoparticles by in situ chemical oxidative polymerization

摘要

Core-shell nanocomposites composed of iron oxide (Fe_3O_4) nanoparticles and conjugated polymer, poly(3, 4-ethylenedioxythiophene) (PEDOT), were successfully synthesized from a simple and inexpensive in situ chemical oxidative polymerization of EDOT with Fe_3O_4 nanoparticles in the micellar solution of lignosulfonic acid (LSA) which serves as both a surfactant and a dopant. These nanocomposites (Fe_3O_4-PEDOT) were subsequently characterized for morphological, crystalline, structural, electrical and magnetic properties by high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), four-probe meter and superconductor quantum interference device (SQUID), respectively. Results show that the nanocomposites have a spherical core-shell shape, are ～10 nm in size and are superparamagnetic with good magnetic saturation and good electrical conductivities. Existence of Fe_3O_4 in the nanocomposites was confirmed by using Energy dispersive X-ray photoelectron spectroscopy (EDAX) and X-ray photoelectron microscopy (XPS). We also investigated a possible formation mechanism of the core-shell nanocomposites, and the effect of Fe_3O_4 nanoparticles on the electro-magnetic properties of the nanocomposites. Such novel conducting and superparamagnetic composite nanomaterials can be applied to sensors, magnetic data storage, electro-magnetic resonance wave absorption, etc.